package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.RedisData;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

@Slf4j
@Component
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;
//  正常ttl过期，用于解决缓存击穿
    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }
    public void set(String key, Object value, Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }
    //逻辑过期，用于热点缓存
    public void setWithLogicalExpire(String key,Object value,Long time,TimeUnit unit){
        RedisData redisData=new RedisData();
        redisData.setData(value);
        redisData.setExpire(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }


    public <R,ID> R queryWithPassThrough(String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback,Long time,TimeUnit unit ){
        String key=keyPrefix+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        if (StrUtil.isNotBlank(shopJson)) {
            return JSONUtil.toBean(shopJson, type);
        }

        if (shopJson != null) {
            return null;
        }

        R r = dbFallback.apply(id);
        if (r == null) {
            stringRedisTemplate.opsForValue().set(key, "",RedisConstants.CACHE_NULL_TTL
                    , TimeUnit.MINUTES);
            return null;
        }

       this.set(key,r,time,unit);
        return r;
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);


    public <R,ID,M,N> R queryWithLogicalExpire(String keyPrefix,ID id,Class<R> type,Function<ID,R> dbFallback,Long time1,TimeUnit unit) {
        String key=keyPrefix+id;
        String json = stringRedisTemplate.opsForValue().get(key);

        if (StrUtil.isBlank(json)) {
            return null;
        }
        RedisData redisData = JSONUtil.toBean(json,RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime time = redisData.getExpire();
        if (time.isAfter(LocalDateTime.now())){
            return r;
        }
        //已过期，重建缓存

        String lockKey=RedisConstants.LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        if (isLock){
            //获取成功直接创建线程，然后缓存重建
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    R r1=dbFallback.apply(id);
                    this.setWithLogicalExpire(key,r1,time1,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(lockKey);
                }
            });

        }

        return r;
    }
    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unLock(String key) {
        stringRedisTemplate.delete(key);
    }
}
